Effect of canopy gaps area on soil biological activities and organic matter fractions in a Beech forest stand

In forest ecosystems, canopy gaps play an essential role in soil nutrient cycling. In this study, the relationship among different areas of canopy gaps (200, 400, 600 and > 600 m2), biological (e.g., earthworm biomass, microbial respiration, N mineralization, C microbial biomass, N microbial biomass and particulate organic matter of C and N) and also physico-chemical (e.g., bulk density, texture, moisture, pH, organic C, total N and available P, K and Ca) properties, from the top 15 cm of soil, was studied in Beech forests of Sardabrood located in Kelarabad. Three points were considered in center of each canopy gap and also closed canopy, soil samples were taken and mixed due to transferring to laboratory for analysis. According to findings, whole of soil physico-chemical properties (except for silt content and available Ca) were significantly affected by different canopy gaps areas. Also, the highest earthworm's assemblage was under closed canopy and the population was decreased with increasing of canopy gap areas. The characters of microbial respiration, N mineralization and particulate organic of C and N showed ascending trend with increasing of canopy gap areas. Carbon microbial biomass was significantly higher under closed canopy than in different canopy gap areas, whereas the highest amount of N microbial biomass was found within 400 m2 gap areas. According to our data, the highest values of soil chemical and biological properties were related to 400 m2 gap areas. In larger canopy gap areas, soil nutrient elements are decreased due to high decomposition and leaching.